1. Technical Field
The present invention relates to an image forming apparatus or the like that performs a process of supplying colorants for each color, and more particularly to an image forming apparatus or the like that can efficiently perform a correction process with respect to misregistration occurring due to the process of supplying colorants, without causing degradation of image quality.
2. Related Art
In an image forming apparatus such as a laser printer, a process of attaching colorants of each color to a sheet, an intermediate medium or a photosensitive body by supplying the colorants thereto is performed independent of each color. A case may occur in which formed images of each color are relatively out of alignment depending on the mechanical accuracy of the apparatus. If such misregistration (also called color shift) occurs, it adversely affects the output quality, for example, producing white portions (voids) that have not been initially present on the boundaries between characters and background. In this regard, a process of correcting in advance image data to be output has been performed to prevent defects caused by such misregistration.
Japanese Patent No. 3852234 suggests an apparatus that effectively prevents so-called edge light coloring and performs a rapid process. Further, JP-A-2002-165104 discloses an apparatus that performs a trapping process such that an object seems to be of the same order as an actual one even if printing deviation occurs.
However, in the apparatus of Japanese Patent No. 3852234, since a region where image data is corrected is determined in object units of an image, when objects such as characters or graphics, which have to be corrected originally, are incorporated into objects such as images, which are not corrected, in an application level of supplying image data, correction is not performed with respect to these objects, so that a correction process is not reliably performed. Further, image data received in an image forming apparatus such as a printer is represented by a PDL of various formats, and the classification of objects is established for each format. Therefore, in the aforementioned process in object units, respective processing procedures have to be prepared for each format and the process becomes complicated and inefficient.
Further, in the apparatus of JP-A-2002-165104, a process of establishing a correction range and a correction color by the brightness difference between adjacent regions may become complicated.
On the other hand, in the most general usage mode of image forming apparatuses, a void caused by the misregistration that occurs between a black character or graphic and a color background is a serious problem. However, no method for resolving this problem has been suggested.
In this regard, a method for efficiently resolving this problem is needed in a process in pixel units that is considered to be a time-consuming process.